Many items of heavy machinery such as used in mining operations utilize driven pads which carry a plurality of drive members on their inner surface. These members are engaged by the drive tumbler of the machine to induce relative motion between the pad and the machine. An example of this type machinery is the Hitachi.RTM. 3500 XE. Heretofore, it was determined to be less expensive and less time-consuming to replace the drive tumblers than to replace the pad in this type machinery. Therefore, the drive members on the pads have been made to withstand the wear of engagement and disengagement with the tumbler, whereas the tumblers readily become worn and must be replaced. As might be imagined the replacement of a metal wheel five feet in diameter and ten inches thick is not an easy task. However, the wear at the point of contact between the pad drive members and the tumbler (wheel) necessitates the frequent replacement thereof Accordingly, there exists a need for a construction of such tumblers which would substantially reduce the effort and time required to repair worn surfaces on the tumblers.